STORY: Later, they will travel to the Welsh Parliament, commonly known as the Senedd, to receive a Motion of Condolence.
Charles will meet the Welsh first minister and other politicians before attending a reception at Cardiff Castle.
The trip marks the last stop on a tour of the United Kingdom where he has performed ceremonial duties to acknowledge his status as the new monarch and head of state, and to greet the public mourning the loss of Queen Elizabeth, who reigned for 70 years.
Wales has a particular significance for the new king. For five decades preceding last week's accession he had the title Prince of Wales - longer than anyone previously.
Britain is gearing up to welcome presidents, prime ministers and royalty from around the world for Monday's (September 19) funeral, which is likely to be one of the grandest ceremonies ever seen in the British capital, involving thousands of military personnel.